there is Hiragana, Katakana, Furi kana, Kanji, Romajii, Kaisho....and more

-furigana is just kana on top or to the right of kanji that isn't commonly known in Japanese or used in children's books ... so it's not actually a form of writing.
-Romajii uses the alphabet and is just a way to show pronunciation of words,...
-kaisho is a caligrahy font

the japanese language is therefor only comprised of Hiragana, Katakana & Kanji.